Mimic A/D conversion
# from https://dsp.stackexchange.com/questions/33596/analog-to-digital-conversion-using-python
import numpy as np
import matplotlib.pyplot as plt
time_of_view = 1.0
analog_time = np.linspace(0, time_of_view, num=100)
sampling_rate = 21.0 # s.
sampling_period = 1.0 / sampling_rate # s.
sample_number = time_of_view / sampling_period
sampling_time = np.linspace(0, time_of_view, int(sample_number)) # Hz
carrier_frequency = 9.0 # s
amplitude = 1
phase = 0
quantizing_bits = 4
quantizing_levels = 2 ** quantizing_bits / 2 # Hz
quantizing_step = 1.0 / quantizing_levels # V
# deg
def analog_signal(time_point):
return amplitude * np.cos(2 * np.pi * carrier_frequency * time_point + phase)
sampling_signal = analog_signal(sampling_time)
quantizing_signal = np.round(sampling_signal / quantizing_step) * quantizing_step
_fig = plt.figure()
plt.stem(sampling_time, quantizing_signal, linefmt='r-', markerfmt='rs', basefmt='r-')
plt.title('Analog to digital signal conversion')
plt.xlabel('Time')
plt.ylabel('Amplitude')
# plt.plot (analog_time, analog_signal (analog_time) );
#plt.stem (sampling_time, sampling_signal);
plt.show()
_fig = plt.figure()
plt.plot(analog_time, analog_signal(analog_time))
#plt.stem (sampling_time, sampling_signal);
plt.stem(sampling_time, quantizing_signal, linefmt='r-', markerfmt='rs', basefmt='r-')
plt.title('Analog to digital signal conversion')
plt.xlabel('Time')
plt.ylabel('Amplitude')
